This invention relates to a power supply module having an internal energy storage circuit.
The electrical power consumption of gas-powered and diesel-powered vehicles is expected to increase as more elaborate electrical features are introduced into vehicles. For example, a typical automobile may require an electrical system with a capacity of more than 3 kilowatts in the future. To meet increased peak power requirements, vehicle manufacturers may adopt higher voltage electrical systems than customary systems that support 12 volt batteries.
However, many electrical accessories, such as lamps, are designed to operate with a lower voltage source in the neighborhood of 12 volts direct current. Although a filament of a lamp may be lengthened or the wire gauge of the filament may be reduced to be compatible with a 36 volt or higher battery supply, longer or thinner filaments lack the durability of their lower voltage counterparts. Vehicle manufacturers may not want to make the tradeoff of lower reliability attendant with higher voltage lamps in the vehicular environment. Thus, a need exists for a power supply module that makes a higher voltage supply compatible with a lower voltage load.
Wiring harnesses are used throughout vehicles to provide power or control signals to circuitry or passive components distributed throughout the vehicle. Wiring harnesses are frequently pulled through or otherwise routed in cramped spaces internally within the vehicle. Wiring harnesses generally become more bulky, difficult to install, and expensive as the number of wires in the harness increase to support various electrical features. Thus, a need exists to reduce the complexity of wiring within the vehicle, while reaping the advantages of the aforementioned higher voltage electrical system.
In accordance with the invention, a power supply module has an internal energy storage circuit to reduce the number of external wire connections to the power supply module. The power supply module is used to provide pulsed electrical energy to a load. The power supply module includes a semiconductor switch, an oscillator, and an energy storage circuit. The semiconductor switch has a first state for placing electrical potential across terminals of a load at a supply voltage level and a second state for placing no electrical potential across the terminals. The oscillator alternately activates the semiconductor switch to achieve the first state for a first duration and the second state for a second duration. The oscillator is controlled to apply an average voltage (e.g., root mean squared voltage) of a lesser voltage level than the supply voltage level to the load. The energy storage circuit accumulates energy for providing electrical energy to the oscillator to maintain stable, active operation of the oscillator.
The power supply module of the invention supports a higher voltage electrical system that allows lower amperage components and wires to be used to supply the same peak power as a lower voltage system. A higher voltage electrical system may handle more electrical features or more power intensive electrical features for the same size of wiring within the vehicle. Alternatively, the cross-sectional size of the wiring may be decreased to provide the same capacity of electrical power as a lower voltage electrical system.
The power supply module of the invention includes as few as two external terminals (e.g., a load terminal and a ground terminal) for external electrical connection. Accordingly, the external packaging of the power supply module is relatively simple and may be composed of a dielectric with provisions for just two external conductors that are connected to the internal circuitry of the power supply module. The power supply module may be installed quickly and accurately because as few as one supply wire is required to feed the load terminal with an energy source. Where multiple power supply modules are used in a vehicle, an overall reduction in the number of requisite supply wires may lead to simplified wiring and reduced assembly time for the vehicle. Further, the elimination of some wires may reduce the space required for routing wiring harnesses through the vehicle and reduce the cost of a wiring harness.